1. Field of the Invention
This invention is related to a method and apparatus for monitoring optical radiation and, more particularly, to a method and apparatus for determining and monitoring hazardous ultraviolet radiation levels which may be emanating from optical radiation sources.
2. Description of the Prior Art
It is known that the deleterious biological effects to human beings which may be caused by exposure to ultraviolet radiant energy are highly wavelength dependent. That is, certain acute inflammatory skin reactions of humans are known to be caused by ultraviolet radiation of a certain wavelength range, while other biological effects result from ultraviolet radiation of a different wavelength. Further, some wavelengths of ultraviolet radiation have a markedly greater effect than other wavelengths.
Prior art ultraviolet hazard monitoring techniques have relied upon the utilization of conventional photodetector tubes for detecting the ultraviolet radiation, which have wavelength-dependent responses. In order to determine the energy per unit wavelength, the radiant energy is dispersed into a spectrum and the detector views only a portion of the spectrum at any one time. The results from such measurements must then be mathematically weighted in accordance with the biological effects curve, known as the action spectrum, in order to result in a biologically meaningful output. This procedure is to a great extent manual, tedious, time consuming, and prone to great error.
Accordingly, when designing a instrument for effective monitoring of such ultraviolet radiation, which may emanate from common electronic product sources, in order to detect hazardous levels, it is necessary not only to provide an instrument in which the intensity of the radiation is measurable but also one which weights its response according to any predetermined wavelength-dependent action spectrum to take into account biological effects. This is desirable in order that the output of the instrument provides a direct indication of the potential hazard from ultraviolet radiation present.
Prior art instruments have attempted to incorporate means for taking into account biological effects by shaping the response function of the wavelength-dependent detectors with fixed filters to match the shape of the biological effects response. The fabrication of such biologically weighted filters is extremely expensive since it is quite difficult to match the physical characteristics of such filters with the biological response desired. Further, any changes in the biological weighting to accommodate the various action spectra for deleterious biological effects, as well as any changes in the biological weighting as a result of new research, cannot easily or inexpensively be incorporated into such instruments. Since continuing biological experimentation results in increasingly refined wavelength-dependent biological response functions, it is quite important to be able to accommodate such updated data inexpensively and quickly.